Toilets use a substantial amount of water in their operation and it is naturally desirable to avoid waste of any water if possible. This is especially true for commercial users having large numbers of toilets, such as hotels and motels, and those living in areas where water is in short supply.
One common source of wasted water relates to the volume of water delivered by each flush of the tank. For many users it is not necessary to have their tank deliver the maximum amount of water during each flush cycle, and a substantial amount of water can be conserved by reducing this volume. Hence, it is desirable to be able to conveniently control the volume of water a tank will deliver when flushed. Moreover, in some areas water shortages are only temporary, in which case a user may wish to conserve water only during a shortage period and return to normal flush volume after the shortage is over. In such situations, the convenience with which water volume can be adjusted is especially important.
Leaks are another potentially significant source of wasted water. Leaks often develop around the edges of the flush tank stopper valve as the stopper gets old and begins to deteriorate. With these leaks water drains slowing into the toilet bowl and can go undetected for a long period of time. Leaks also may develop at the base of the ballcock water supply line or through cracks in the tank, in which case water drains to the floor around the toilet causing potentially serious damage.
With a typical ballcock system, when water level in the tank falls below a certain level due to leakage, the ballcock simply activates water flow and refills the tank. Thus, because the tank is being perpetually refilled, leaking can continue indefinitely. Over time, a huge amount of water can be wasted or, worse, very extensive damage caused. There is a particularly great risk that such leaks will go undetected in situations, as in hotels and motels, where a toilet may not be used for substantial periods of time.